💾 Archived View for 80h.dev › agena › gopherpedia.com › 0 › SMS captured on 2020-09-24 at 00:49:02.
-=-=-=-=-=-=-
======================================================================
= SMS =
======================================================================
Introduction
======================================================================
SMS (short message service) is a text messaging service component of
most telephone, Internet, and mobile device systems. It uses
standardized communication protocols to enable mobile devices to
exchange short text messages. An intermediary service can facilitate a
text-to-voice conversion to be sent to landlines.
SMS, as used on modern devices, originated from radio telegraphy in
radio memo pagers that used standardized phone protocols. These were
defined in 1985 as part of the Global System for Mobile Communications
(GSM) series of standards. The first test SMS message was sent in 1992
and it commercially rolled out to many cellular networks that decade.
SMS became hugely popular worldwide as a way of text communication. By
the end of 2010, SMS was the most widely used data application, with
an estimated 3.5 billion active users, or about 80% of all mobile
phone subscribers.
The protocols allowed users to send and receive messages of up to 160
characters (when entirely alpha-numeric) to and from GSM mobiles.
Although most SMS messages are sent from one mobile phone to another,
support for the service has expanded to include other mobile
technologies, such as ANSI CDMA networks and Digital AMPS.
Mobile marketing, a type of direct marketing, uses SMS. According to a
2014 market research report the global SMS messaging business was
estimated to be worth over US$100 billion, accounting for almost 50
percent of all the revenue generated by mobile messaging.
Initial concept
=================
Adding text messaging functionality to mobile devices began in the
early 1980s. The first action plan of the CEPT Group GSM was approved
in December 1982, requesting that "The services and facilities offered
in the public switched telephone networks and public data networks ...
should be available in the mobile system." This plan included the
exchange of text messages either directly between mobile stations, or
transmitted via message handling systems in use at that time.
The SMS concept was developed in the Franco-German GSM cooperation in
1984 by Friedhelm Hillebrand and Bernard Ghillebaert. The GSM is
optimized for telephony, since this was identified as its main
application. The key idea for SMS was to use this telephone-optimized
system, and to transport messages on the signalling paths needed to
control the telephone traffic during periods when no signalling
traffic existed. In this way, unused resources in the system could be
used to transport messages at minimal cost. However, it was necessary
to limit the length of the messages to 128 bytes (later improved to
160 seven-bit characters) so that the messages could fit into the
existing signalling formats. Based on his personal observations and on
analysis of the typical lengths of postcard and Telex messages,
Hillebrand argued that 160 characters was sufficient for most brief
communications.
SMS could be implemented in every mobile station by updating its
software. Hence, a large base of SMS-capable terminals and networks
existed when people began to use SMS. A new network element required
was a specialized short message service centre, and enhancements were
required to the radio capacity and network transport infrastructure to
accommodate growing SMS traffic.
Early development
===================
The technical development of SMS was a multinational collaboration
supporting the framework of standards bodies. Through these
organizations the technology was made freely available to the whole
world.
The first proposal which initiated the development of SMS was made by
a contribution of Germany and France in the GSM group meeting in
February 1985 in Oslo. This proposal was further elaborated in GSM
subgroup WP1 Services (Chairman Martine Alvernhe, France Telecom)
based on a contribution from Germany. There were also initial
discussions in the subgroup WP3 network aspects chaired by Jan
Audestad (Telenor). The result was approved by the main GSM group in a
June 1985 document which was distributed to industry. The input
documents on SMS had been prepared by Friedhelm Hillebrand of Deutsche
Telekom, with contributions from Bernard Ghillebaert of France
Télécom. The definition that Friedhelm Hillebrand and Bernard
Ghillebaert brought into GSM called for the provision of a message
transmission service of alphanumeric messages to mobile users "with
acknowledgement capabilities". The last three words transformed SMS
into something much more useful than the electronic paging services
used at the time that some in GSM might have had in mind.
SMS was considered in the main GSM group as a possible service for the
new digital cellular system. In GSM document "'Services and Facilities
to be provided in the GSM System,'" both mobile-originated and
mobile-terminated short messages appear on the table of GSM
teleservices.
The discussions on the GSM services were concluded in the
recommendation GSM 02.03 "'TeleServices supported by a GSM PLMN.'"
Here a rudimentary description of the three services was given:
# Short message mobile-terminated (SMS-MT)/ Point-to-Point: the
ability of a network to transmit a Short Message to a mobile phone.
The message can be sent by phone or by a software application.
# Short message mobile-originated (SMS-MO)/ Point-to-Point: the
ability of a network to transmit a Short Message sent by a mobile
phone. The message can be sent to a phone or to a software
application.
# Short message cell broadcast.
The material elaborated in GSM and its WP1 subgroup was handed over in
Spring 1987 to a new GSM body called IDEG (the Implementation of Data
and Telematic Services Experts Group), which had its kickoff in May
1987 under the chairmanship of Friedhelm Hillebrand (German Telecom).
The technical standard known today was largely created by IDEG (later
WP4) as the two recommendations GSM 03.40 (the two point-to-point
services merged) and GSM 03.41 (cell broadcast).
WP4 created a Drafting Group Message Handling (DGMH), which was
responsible for the specification of SMS. Finn Trosby of Telenor
chaired the draft group through its first 3 years, in which the design
of SMS was established. DGMH had five to eight participants, and Finn
Trosby mentions as major contributors Kevin Holley, Eija Altonen,
Didier Luizard and Alan Cox. The first action plan mentions for the
first time the Technical Specification 03.40 "Technical Realisation of
the Short Message Service". Responsible editor was Finn Trosby. The
first and very rudimentary draft of the technical specification was
completed in November 1987. However, drafts useful for the
manufacturers followed at a later stage in the period. A comprehensive
description of the work in this period is given in.
The work on the draft specification continued in the following few
years, where Kevin Holley of Cellnet (now Telefónica O2 UK) played a
leading role. Besides the completion of the main specification GSM
03.40, the detailed protocol specifications on the system interfaces
also needed to be completed.
Support in other architectures
================================
The Mobile Application Part (MAP) of the SS7 protocol included support
for the transport of Short Messages through the Core Network from its
inception. MAP Phase 2 expanded support for SMS by introducing a
separate operation code for Mobile Terminated Short Message transport.
Since Phase 2, there have been no changes to the Short Message
operation packages in MAP, although other operation packages have been
enhanced to support CAMEL SMS control.
From 3GPP Releases 99 and 4 onwards, CAMEL Phase 3 introduced the
ability for the Intelligent Network (IN) to control aspects of the
Mobile Originated Short Message Service, while CAMEL Phase 4, as part
of 3GPP Release 5 and onwards, provides the IN with the ability to
control the Mobile Terminated service. CAMEL allows the gsmSCP to
block the submission (MO) or delivery (MT) of Short Messages, route
messages to destinations other than that specified by the user, and
perform real-time billing for the use of the service. Prior to
standardized CAMEL control of the Short Message Service, IN control
relied on switch vendor specific extensions to the Intelligent Network
Application Part (INAP) of SS7.
Early implementations
=======================
The first SMS message was sent over the Vodafone GSM network in the
United Kingdom on 3 December 1992, from Neil Papworth of Sema Group
(now Mavenir Systems) using a personal computer to Richard Jarvis of
Vodafone using an Orbitel 901 handset. The text of the message was
"Merry Christmas."
The first commercial deployment of a short message service center
(SMSC) was by Aldiscon part of Logica (now part of CGI) with Telia
(now TeliaSonera) in Sweden in 1993, followed by Fleet Call (now
Nextel) in the US, Telenor in Norway and BT Cellnet (now O2 UK) later
in 1993. All first installations of SMS gateways were for network
notifications sent to mobile phones, usually to inform of voice mail
messages.
The first commercially sold SMS service was offered to consumers, as a
person-to-person text messaging service by Radiolinja (now part of
Elisa) in Finland in 1993. Most early GSM mobile phone handsets did
not support the ability to send SMS text messages, and Nokia was the
only handset manufacturer whose total GSM phone line in 1993 supported
user-sending of SMS text messages. According to Matti Makkonen, an
engineer at Nokia at the time, the Nokia 2010, which was released in
January 1994, was the first mobile phone to support composing SMSes
easily.
Initial growth was slow, with customers in 1995 sending on average
only 0.4 messages per GSM customer per month. One factor in the slow
takeup of SMS was that operators were slow to set up charging systems,
especially for prepaid subscribers, and eliminate billing fraud which
was possible by changing SMSC settings on individual handsets to use
the SMSCs of other operators. Initially, networks in the UK only
allowed customers to send messages to other users on the same network,
limiting the usefulness of the service. This restriction was lifted in
1999.
Over time, this issue was eliminated by switch billing instead of
billing at the SMSC and by new features within SMSCs to allow blocking
of foreign mobile users sending messages through it. By the end of
2000, the average number of messages reached 35 per user per month,
and on Christmas Day 2006, over 205 million messages were sent in the
UK alone.
Text messaging outside GSM
============================
SMS was originally designed as part of GSM, but is now available on a
wide range of networks, including 3G networks. However, not all text
messaging systems use SMS, and some notable alternative
implementations of the concept include J-Phone's 'SkyMail' and NTT
Docomo's 'Short Mail', both in Japan. Email messaging from phones, as
popularized by NTT Docomo's i-mode and the RIM BlackBerry, also
typically uses standard mail protocols such as SMTP over TCP/IP.
SMS today
===========
, 6.1 trillion (6.1 × 1012) SMS text messages were sent, which is an
average of 193,000 SMS per second. SMS has become a large commercial
industry, earning $114.6 billion globally in 2010. The global average
price for an SMS message is US$0.11, while mobile networks charge each
other interconnect fees of at least US$0.04 when connecting between
different phone networks.
In 2015, the actual cost of sending an SMS in Australia was found to
be $0.00016 per SMS.
In 2014, Caktus Group developed the world's first SMS-based voter
registration system in Libya. So far, more than 1.5 million people
have registered using that system, providing Libyan voters with
unprecedented access to the democratic process.
While SMS is still a growing market, it is being increasingly
challenged by Internet Protocol-based messaging services such as
Apple's iMessage, Facebook Messenger, WhatsApp, Viber, WeChat (in
China) and Line (in Japan), available on smart phones with data
connections. It has been reported that over 97% of smart phone owners
use alternative messaging services at least once a day. However, in
the U.S. these Internet-based services have not caught on as much, and
SMS continues to be highly popular there.
SMS Enablement
================
SMS enablement allows individuals to send an SMS message to a business
phone number (traditional landline) and receive a SMS in return.
Providing customers with the ability to text to a phone number allows
organizations to offer new services that deliver value. Examples
include chat bots, and text enabled customer service and call centers.
GSM
=====
The 'Short Message Service—Point to Point (SMS-PP)'—was originally
defined in GSM recommendation 03.40, which is now maintained in 3GPP
as TS 23.040. GSM 03.41 (now 3GPP TS 23.041) defines the 'Short
Message Service—Cell Broadcast (SMS-CB)', which allows messages
(advertising, public information, etc.) to be broadcast to all mobile
users in a specified geographical area.
Messages are sent to a short message service center (SMSC), which
provides a "store and forward" mechanism. It attempts to send messages
to the SMSC's recipients. If a recipient is not reachable, the SMSC
queues the message for later retry. Some SMSCs also provide a "forward
and forget" option where transmission is tried only once. Both mobile
terminated (MT, for messages sent 'to' a mobile handset) and mobile
originating (MO, for those sent 'from' the mobile handset) operations
are supported. Message delivery is "best effort", so there are no
guarantees that a message will actually be delivered to its recipient,
but delay or complete loss of a message is uncommon, typically
affecting less than 5 percent of messages. Some providers allow users
to request delivery reports, either via the SMS settings of most
modern phones, or by prefixing each message with *0# or *N#. However,
the exact meaning of confirmations varies from reaching the network,
to being queued for sending, to being sent, to receiving a
confirmation of receipt from the target device, and users are often
not informed of the specific type of success being reported.
SMS is a stateless communication protocol in which every SMS message
is considered entirely independent of other messages. Enterprise
applications using SMS as a communication channel for stateful
dialogue (where an MO reply message is paired to a specific MT
message) requires that session management be maintained external to
the protocol.
Message size
==============
Transmission of short messages between the SMSC and the handset is
done whenever using the Mobile Application Part (MAP) of the SS7
protocol. Messages are sent with the MAP MO- and MT-ForwardSM
operations, whose payload length is limited by the constraints of the
signaling protocol to precisely 140 bytes (140 bytes * 8 bits / byte =
1120 bits).
Short messages can be encoded using a variety of alphabets: the
default GSM 7-bit alphabet, the 8-bit data alphabet, and the 16-bit
UCS-2 alphabet. Depending on which alphabet the subscriber has
configured in the handset, this leads to the maximum individual short
message sizes of 160 7-bit characters, 140 8-bit characters, or 70
16-bit characters. GSM 7-bit alphabet support is mandatory for GSM
handsets and network elements, but characters in languages such as
Hindi, Arabic, Chinese, Korean, Japanese, or Cyrillic alphabet
languages (e.g., Russian, Ukrainian, Serbian, Bulgarian, etc.) must be
encoded using the 16-bit UCS-2 character encoding (see Unicode).
Routing data and other metadata is additional to the payload size.
Larger content (concatenated SMS, multipart or segmented SMS, or "long
SMS") can be sent using multiple messages, in which case each message
will start with a User Data Header (UDH) containing segmentation
information. Since UDH is part of the payload, the number of available
characters per segment is lower: 153 for 7-bit encoding, 134 for 8-bit
encoding and 67 for 16-bit encoding. The receiving handset is then
responsible for reassembling the message and presenting it to the user
as one long message. While the standard theoretically permits up to
255 segments, 10 segments is the practical maximum with some carriers,
and long messages are often billed as equivalent to multiple SMS
messages. Some providers have offered length-oriented pricing schemes
for messages, although that type of pricing structure is rapidly
disappearing.
Gateway providers
===================
SMS gateway providers facilitate SMS traffic between businesses and
mobile subscribers, including SMS for enterprises, content delivery,
and entertainment services involving SMS, e.g. TV voting. Considering
SMS messaging performance and cost, as well as the level of messaging
services, SMS gateway providers can be classified as aggregators or
SS7 providers.
The aggregator model is based on multiple agreements with mobile
carriers to exchange two-way SMS traffic into and out of the
operator's SMSC, also known as "local termination model". Aggregators
lack direct access into the SS7 protocol, which is the protocol where
the SMS messages are exchanged. SMS messages are delivered to the
operator's SMSC, but not the subscriber's handset; the SMSC takes care
of further handling of the message through the SS7 network.
Another type of SMS gateway provider is based on SS7 connectivity to
route SMS messages, also known as "international termination model".
The advantage of this model is the ability to route data directly
through SS7, which gives the provider total control and visibility of
the complete path during SMS routing. This means SMS messages can be
sent directly to and from recipients without having to go through the
SMSCs of other mobile operators. Therefore, it is possible to avoid
delays and message losses, offering full delivery guarantees of
messages and optimized routing. This model is particularly efficient
when used in mission-critical messaging and SMS used in corporate
communications. Moreover, these SMS gateway providers are providing
branded SMS services with masking but after misuse of these gateways
most countries's Governments have taken serious steps to block these
gateways.
Interconnectivity with other networks
=======================================
Message Service Centers communicate with the Public Land Mobile
Network (PLMN) or PSTN via Interworking and Gateway MSCs.
Subscriber-originated messages are transported from a handset to a
service center, and may be destined for mobile users, subscribers on a
fixed network, or Value-Added Service Providers (VASPs), also known as
application-terminated. Subscriber-terminated messages are
transported from the service center to the destination handset, and
may originate from mobile users, from fixed network subscribers, or
from other sources such as VASPs.
On some carriers nonsubscribers can send messages to a subscriber's
phone using an Email-to-SMS gateway. Additionally, many carriers,
including AT&T Mobility, T-Mobile USA, Sprint, and Verizon
Wireless, offer the ability to do this through their respective web
sites.
For example, an AT&T subscriber whose phone number was
555-555-5555 would receive e-mails addressed to 5555555555@txt.att.net
as text messages. Subscribers can easily reply to these SMS messages,
and the SMS reply is sent back to the original email address. Sending
email to SMS is free for the sender, but the recipient is subject to
the standard delivery charges. Only the first 160 characters of an
email message can be delivered to a phone, and only 160 characters can
be sent from a phone. However, longer messages may be broken up into
multiple texts, depending upon the telephone service provider.
Text-enabled fixed-line handsets are required to receive messages in
text format. However, messages can be delivered to nonenabled phones
using text-to-speech conversion.
Short messages can send binary content such as ringtones or logos, as
well as Over-the-air programming (OTA) or configuration data. Such
uses are a vendor-specific extension of the GSM specification and
there are multiple competing standards, although Nokia's Smart
Messaging is common. An alternative way for sending such binary
content is EMS messaging, which is standardized and not dependent on
vendors.
SMS is used for M2M (Machine to Machine) communication. For instance,
there is an LED display machine controlled by SMS, and some vehicle
tracking companies use SMS for their data transport or telemetry
needs. SMS usage for these purposes is slowly being superseded by GPRS
services owing to their lower overall cost. GPRS is offered by smaller
telco players as a route of sending SMS text to reduce the cost of SMS
texting internationally.
AT commands
=============
Many mobile and satellite transceiver units support the sending and
receiving of SMS using an extended version of the Hayes command set.
The extensions were standardised as part of the GSM Standards and
extended as part of the 3GPP standards process.
The connection between the terminal equipment and the transceiver can
be realized with a serial cable (e.g., USB), a Bluetooth link, an
infrared link, etc. Common AT commands include AT+CMGS (send message),
AT+CMSS (send message from storage), AT+CMGL (list messages) and
AT+CMGR (read message).
However, not all modern devices support receiving of messages if the
message storage (for instance the device's internal memory) is not
accessible using AT commands.
Premium-rated short messages
==============================
Short messages may be used normally to provide premium rate services
to subscribers of a telephone network.
Mobile-terminated short messages can be used to deliver digital
content such as news alerts, financial information, logos, and ring
tones. The first premium-rate media content delivered via the SMS
system was the world's first paid downloadable ringing tones, as
commercially launched by Saunalahti (later Jippii Group, now part of
Elisa Group), in 1998. Initially, only Nokia branded phones could
handle them. By 2002 the ringtone business globally had exceeded $1
billion of service revenues, and nearly US$5 billion by 2008. Today,
they are also used to pay smaller payments online—for example, for
file-sharing services, in mobile application stores, or VIP section
entrance. Outside the online world, one can buy a bus ticket or
beverages from ATM, pay a parking ticket, order a store catalog or
some goods (e.g., discount movie DVDs), make a donation to charity,
and much more.
Premium-rated messages are also used in Donors Message Service to
collect money for charities and foundations. DMS was first launched at
April 1, 2004, and is very popular in the Czech Republic. For example,
the Czech people sent over 1.5 million messages to help South Asia
recover from the 2004 Indian Ocean earthquake and tsunami.
The Value-added service provider (VASP) providing the content submits
the message to the mobile operator's SMSC(s) using an TCP/IP protocol
such as the short message peer-to-peer protocol (SMPP) or the External
Machine Interface (EMI). The SMSC delivers the text using the normal
Mobile Terminated delivery procedure. The subscribers are charged
extra for receiving this premium content; the revenue is typically
divided between the mobile network operator and the VASP either
through revenue share or a fixed transport fee. Submission to the SMSC
is usually handled by a third party.
Mobile-originated short messages may also be used in a premium-rated
manner for services such as televoting. In this case, the VASP
providing the service obtains a short code from the telephone network
operator, and subscribers send texts to that number. The payouts to
the carriers vary by carrier; percentages paid are greatest on the
lowest-priced premium SMS services. Most information providers should
expect to pay about 45 percent of the cost of the premium SMS up front
to the carrier. The submission of the text to the SMSC is identical to
a standard MO Short Message submission, but once the text is at the
SMSC, the Service Center (SC) identifies the Short Code as a premium
service. The SC will then direct the content of the text message to
the VASP, typically using an IP protocol such as SMPP or EMI.
Subscribers are charged a premium for the sending of such messages,
with the revenue typically shared between the network operator and the
VASP. Short codes only work within one country, they are not
international.
An alternative to inbound SMS is based on long numbers (international
number format, such as "+44 762 480 5000"), which can be used in place
of short codes for SMS reception in several applications, such as TV
voting, product promotions and campaigns. Long numbers work
internationally, allow businesses to use their own numbers, rather
than short codes, which are usually shared across many brands.
Additionally, long numbers are nonpremium inbound numbers.
Threaded SMS
==============
Threaded SMS is a visual styling orientation of SMS message history
that arranges messages to and from a contact in chronological order on
a single screen.
It was first invented by a developer working to implement the SMS
client for the BlackBerry, who was looking to make use of the blank
screen left below the message on a device with a larger screen capable
of displaying far more than the usual 160 characters, and was inspired
by threaded Reply conversations in email.
Visually, this style of representation provides a back-and-forth
chat-like history for each individual contact. Hierarchical-threading
at the conversation-level (as typical in blogs and on-line messaging
boards) is not widely supported by SMS messaging clients. This
limitation is due to the fact that there is no session identifier or
subject-line passed back and forth between sent and received messages
in the header data (as specified by SMS protocol) from which the
client device can properly thread an incoming message to a specific
dialogue, or even to a specific message within a dialogue.
Most smart phone text-messaging-clients are able to create some
contextual threading of "group messages" which narrows the context of
the thread around the common interests shared by group members. On
the other hand, advanced enterprise messaging applications which push
messages from a remote server often display a dynamically changing
reply number (multiple numbers used by the same sender), which is used
along with the sender's phone number to create session-tracking
capabilities analogous to the functionality that cookies provide for
web-browsing. As one pervasive example, this technique is used to
extend the functionality of many Instant Messenger (IM) applications
such that they are able to communicate over two-way dialogues with the
much larger SMS user-base. In cases where multiple reply numbers are
used by the enterprise server to maintain the dialogue, the visual
conversation threading on the client may be separated into multiple
threads.
Application-to-person (A2P) SMS
=================================
While SMS reached its popularity as a person-to-person messaging,
another type of SMS is growing fast: application-to-person (A2P)
messaging. A2P is a type of SMS sent from a subscriber to an
application or sent from an application to a subscriber. It is
commonly used by businesses, such as banks, to send SMS messages from
their systems to their customers.
In the US, carriers have traditionally preferred that A2P messages
must be sent using a short code rather than a standard long code.
However, recently multiple US carriers, including Verizon have
announced plans to officially support A2P messages over long codes. In
the United Kingdom A2P messages can be sent with a dynamic 11
character sender ID; however, short codes are used for OPTOUT
commands. There are specialist companies such as MMG Mobile Marketing
Group which provide these services to businesses and enterprises.
Satellite phone networks
==========================
All commercial satellite phone networks except ACeS and OptusSat
support SMS. While early Iridium handsets only support incoming SMS,
later models can also send messages. The price per message varies for
different networks. Unlike some mobile phone networks, there is no
extra charge for sending international SMS or to send one to a
different satellite phone network. SMS can sometimes be sent from
areas where the signal is too poor to make a voice call.
Satellite phone networks usually have web-based or email-based SMS
portals where one can send free SMS to phones on that particular
network.
Unreliability
===============
Unlike dedicated texting systems like the Simple Network Paging
Protocol and Motorola's ReFLEX protocol, SMS message delivery is not
guaranteed, and many implementations provide no mechanism through
which a sender can determine whether an SMS message has been delivered
in a timely manner. SMS messages are generally treated as
lower-priority traffic than voice, and various studies have shown that
around 1% to 5% of messages are lost entirely, even during normal
operation conditions, and others may not be delivered until long after
their relevance has passed. The use of SMS as an emergency
notification service in particular has been questioned.
Vulnerabilities
=================
The Global Service for Mobile communications (GSM), with the greatest
worldwide number of users, succumbs to several security
vulnerabilities. In the GSM, only the airway traffic between the
Mobile Station (MS) and the Base Transceiver Station (BTS) is
optionally encrypted with a weak and broken stream cipher (A5/1 or
A5/2). The authentication is unilateral and also vulnerable. There are
also many other security vulnerabilities and shortcomings.
[http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4756489
Solutions to the GSM Security Weaknesses], Proceedings of the 2nd IEEE
International Conference on Next Generation Mobile Applications,
Services, and Technologies (NGMAST2008), pp. 576-581, Cardiff, UK,
September 2008, Such vulnerabilities are inherent to SMS as one of
the superior and well-tried services with a global availability in the
GSM networks. SMS messaging has some extra security vulnerabilities
due to its store-and-forward feature, and the problem of fake SMS that
can be conducted via the Internet. When a user is roaming, SMS content
passes through different networks, perhaps including the Internet, and
is exposed to various vulnerabilities and attacks. Another concern
arises when an adversary gets access to a phone and reads the previous
unprotected messages.
In October 2005, researchers from Pennsylvania State University
published an analysis of vulnerabilities in SMS-capable cellular
networks. The researchers speculated that attackers might exploit the
open functionality of these networks to disrupt them or cause them to
fail, possibly on a nationwide scale.
SMS spoofing
==============
The GSM industry has identified a number of potential fraud attacks on
mobile operators that can be delivered via abuse of SMS messaging
services. The most serious threat is SMS Spoofing, which occurs when a
fraudster manipulates address information in order to impersonate a
user that has roamed onto a foreign network and is submitting messages
to the home network. Frequently, these messages are addressed to
destinations outside the home network—with the home SMSC essentially
being "hijacked" to send messages into other networks.
The only sure way of detecting and blocking spoofed messages is to
screen incoming mobile-originated messages to verify that the sender
is a valid subscriber and that the message is coming from a valid and
correct location. This can be implemented by adding an intelligent
routing function to the network that can query originating subscriber
details from the home location register (HLR) before the message is
submitted for delivery. This kind of intelligent routing function is
beyond the capabilities of legacy messaging infrastructure.
Limitation
============
In an effort to limit telemarketers who had taken to bombarding users
with hordes of unsolicited messages, India introduced new regulations
in September 2011, including a cap of 3,000 SMS messages per
subscriber per month, or an average of 100 per subscriber per day.
Due to representations received from some of the service providers and
consumers, TRAI (Telecom Regulatory Authority of India) has raised
this limit to 200 SMS messages per SIM per day in case of prepaid
services, and up to 6,000 SMS messages per SIM per month in case of
postpaid services with effect from 1 November 2011. However, it was
ruled unconstitutional by the Delhi high court, but there are some
limitations.
Flash SMS
===========
A Flash SMS is a type of SMS that appears directly on the main screen
without user interaction and is not automatically stored in the inbox.
It can be useful in emergencies, such as a fire alarm or cases of
confidentiality, as in delivering one-time passwords.
Silent SMS
============
In Germany in 2010 almost half a million "silent SMS" messages were
sent by the federal police, customs and the secret service
"Verfassungsschutz" (offices for protection of the constitution).
These silent messages, also known as "silent TMS", "stealth SMS",
"stealth ping" or "Short Message Type 0", are used to locate a person
and thus to create a complete movement profile. They do not show up on
a display, nor trigger any acoustical signal when received. Their
primary purpose was to deliver special services of the network
operator to any cell phone.
See also
======================================================================